Crank for drilling rigs



March 1927' E. E. GREVE 'CRANK FOR DRILLING RIGS Filed Aug. 17, 1922ATTORNEY Patented Mar. 22, 1927.

I i,621,66a

QEFECE.

EDGAR E. GREVE, 0F BELLEVUE, PENNSYLVANIA.

CRANK FOR DRILLING RIGS.

Application filed August 17, 1922. Serial No. 582,527.

This invention relates to a crank construetion, particularly aconstruction "especially adapted for use in earth drilling rigs.

In oil well drilling rigs a shaft is rotated through a band wheel fixedto the shaft. This shaft as heretofore constructed, has a crank keyedthereto. This crank, through a pitman connection, is utilized ineffecting an oscillation of the walking beam. Thus a great deal ofvibration and jar is transmitted through the various fixed connectionsto the entire drilling rig and the tools are prevented from having afree drop in the hole by reason of the walking beam being rigidlycoupled to the shaft which is driven from the engine through the bandwheel.

The present invention has as a primary object the provision of a crankdesigned to allow the tools to have a free downward drop and which willeliminate much of the jar and vibration incident to the presentarrangement now in general use.

The invention may be readily understood by reference to the accompanyingdrawings, in which:

Fig. 1 represents a side view of a walking beam connected with a driveshaft through a crank involving my invention.

Fig. 2 is a side view on a larger scale of the crank.

Fig. 3 is a top plan view.

Fig. 4 is a section on line IVIV of F1g. 2.

In the drawings 5 designates a bearing in which is a shaft 6 having aband wheel 7 keyed thereto. The shaft is adapted to be continuouslyrotated from an engine not shown, but in a manner well understood in theart. The end of the shaft projects beyond bearing 5 and fixed or keyedto this projecting end is a disk 8 which has an overhanging orprojecting lug extending across a portion thereof. In the lug arepockets 9, in which are the heads of contact pins 10, the shanks of thepins projecting through the lug as shown. The pins are yieldably heldwith their shanks so projected by springs 11 held in the pockets byscrew plugs 12. The lug may be counterbalanced on the disk by portion13.

Loose on the projecting end of the shaft so as to be freely rotatable,and disposed. between disk 8 and washer 14 on the end of the shaft is acrank 15. Washer 14; is held in place by bolt 16. The crank has a radialarm 15 which is provided with one or more openings 17 through which thewrist pin 18 of the pitman connection may pass. The pitman, shown inFig. 1, is designated 19 and the walking beam is designated 20.

In operation, assume the crank to be rotated in a clockwise direction,the lug projecting over the crank, as shown in Fig. 2. As long as thecrank is moving through the part of its travel to draw the pitman 19downward, during which time the walking beam is elevating the drillingtools, the lug will transmit motion to the crank. When, however, thecrank is moved past dead cen 'ter on the downward limit of its movement,the weight of the drilling tools on the walking beam will accelerate itsspeed, and it will move freely relatively to disk 8, allowing the toolsto drop freely. When the pitman reaches its upward limit of movement thecrank will remain stationary until the lug on the constantly rotatingshaft comes around into engagement therewith. Two of the pins 10 willfirst contact with the crank and yield, absorbing the force of theinitial contact between the lug and crank.

The other two pins in the lug are for the purpose of taking up shockwhen the shaft rotates in the opposite direction, although they mightsometimes serve to absorb a shock if the crank should be carried aroundtoo far on the downward drop of the tools.

Various changes and modifications may be made in the detail constructionof the device within the contemplation of my invention, and within thescope of the appended claims.

What I claim as my invention is:

1. A crank mechanism comprising a driven shaft, a crank loosely mountedthereon, means fixed to said shaft having a laterally projecting portionhaving two crank engaging faces thereon adapted to move the crank, andyieldably supported contact members on each of said faces of saidprojecting portion for engagement with the crank.

2. A crank mechanism comprising a driven shaft, a crank loosely mountedon the shaft,

a disk secured to said shaft, means on the 1 disk projecting into thepath of movement of the crank whereby said projecting means may transmitmotion to the shaft and a yieldably projected contact pin on saidprojecting means perpendicular thereto.

3. A crank mechanism comprising a driven shaft, a crank loosely mountedon the shaft,

a disk secured to said shaft, means on the disk projecting into the pathof movement of the crank whereby said projecting means may transmitmotion to the crank, a slidable contact pin on said projecting means, aspring for urging the contact pin into projected position, and means forvarying the pressure of the spring.

4. A crank mechanism for drilling rigs comprising a driven shaft, acrank loosely carried thereon. a disk secured to said shaft having alaterally extending lug thereon projecting into the path of movement ofthe crank, said hi having two crank engaging faces thereon disposed in aplane transverse to the disk, said faces being so located as to permitof said crank having only substantially 180 degrees of movement betweenthem.

5. A crank mechanism for drilling rigs comprising a driven shaft, acrank loosely carried thereon, a disk secured to said shaft having alaterally extending lug thereon projecting into the path of movement ofthe crank, said lug having two crank engaging faces thereon disposed ina plane transverse to the disk, said faces being so located as topermitof said crank having only substantially 1.80 degrees of movementbetween them, and resilient crank engaging means on each face.

In testimony whereof I afiix my signature.

EDGAR E. GREVE.

